We report the result from the first search for D0 decays to invisible final states. The analysis is performed on a data sample of 924 fb−1 collected at and near the ϒ(4S) and ϒ(5S) resonances with ...the Belle detector at the KEKB asymmetric-energy e+e− collider. The absolute branching fraction is determined using an inclusive D0 sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of 9.4×10−5 is set on the branching fraction of D0 to invisible final states at 90% confidence level.
Here, we discuss the first observation of the radiative charm decay D0 → ρ0γ and the first search for CP violation in decays D0 → ρ0γ , φγ , and K ¯ *0 ( 892 ) γ , using a data sample of 943fb-1 ...collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The branching fraction is measured to be B ( D0 → ρ0γ ) = ( 1.77±0.30±0.07 ) ×10-5 , where the first uncertainty is statistical and the second is systematic. The obtained CP asymmetries A CP ( D0 → ρ0γ ) =+0.056±0.152±0.006 , A CP ( D0 → φγ ) = -0.094±0.066±0.001 , and A CP ( D0 → K ¯ *0γ ) =-0.003±0.020±0.000 are consistent with no CP violation. Furthermore, we present an improved measurement of the branching fractions B ( D0 → φγ ) = ( 2.76±0.19±0.10 ) ×10-5 and B ( D0 → K ¯ *0γ ) = ( 4.66±0.21±0.21 ) ×10-4 .
We present an analysis of the exclusive B+ → π+ π− ℓ+ νℓ decay, where ℓ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The study ...exploits the full Υ ( 4 S ) data sample collected by the Belle detector, corresponding to 711 fb−1 of integrated luminosity. Events are selected by fully reconstructing one B meson in hadronic decay modes, subsequently determining the properties of the other B meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of B(B+ → π+ π− ℓ+ νℓ) = 22.7+1.9 −1.6 (stat) ± 3.5(syst) × 10−5, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.
A
bstract
Using a data sample of 980 fb
−
1
collected with the Belle detector at the KEKB asymmetric-energy
e
+
e
−
collider, we study for the first time the singly Cabibbo-suppressed decays
$$ ...{\Omega}_c^0\to {\Xi}^{-}{\pi}^{+} $$
Ω
c
0
→
Ξ
−
π
+
and Ω
−
K
+
and the doubly Cabibbo-suppressed decay
$$ {\Omega}_c^0\to {\Xi}^{-}{K}^{+} $$
Ω
c
0
→
Ξ
−
K
+
. Evidence for an
$$ {\Omega}_c^0 $$
Ω
c
0
signal in the
$$ {\Omega}_c^0 $$
Ω
c
0
→
Ξ
−
π
+
mode is reported with a significance of 4
.
5
σ
including systematic uncertainties. The ratio of branching fractions to the normalization mode
$$ {\Omega}_c^0 $$
Ω
c
0
→
Ω
−
π
+
is measured to be
$$ \mathcal{B}\left({\Omega}_c^0\to {\Xi}^{-}{\pi}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)=0.253\pm 0.052\left(\textrm{stat}.\right)\pm 0.030\left(\textrm{syst}.\right). $$
B
Ω
c
0
→
Ξ
−
π
+
/
B
Ω
c
0
→
Ω
−
π
+
=
0.253
±
0.052
stat
.
±
0.030
syst
.
.
No significant signals of
$$ {\Omega}_c^0\to {\Xi}^{-}{K}^{+} $$
Ω
c
0
→
Ξ
−
K
+
and Ω
−
K
+
modes are found. The upper limits at 90% confidence level on ratios of branching fractions are determined to be
$$ \mathcal{B}\left({\Omega}_c^0\to {\Xi}^{-}{K}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)<0.070 $$
B
Ω
c
0
→
Ξ
−
K
+
/
B
Ω
c
0
→
Ω
−
π
+
<
0.070
and
$$ \mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{K}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)<0.29. $$
B
Ω
c
0
→
Ω
−
K
+
/
B
Ω
c
0
→
Ω
−
π
+
<
0.29
.
We report a measurement of time-dependent CP violation parameters in B0→KS0ηγ decays. The study is based on a data sample, containing 772×106BB¯ pairs, that was collected at the ϒ(4S) resonance with ...the Belle detector at the KEKB asymmetric-energy e+e− collider. We obtain the CP violation parameters of S=−1.32±0.77(stat)±0.36(syst) and A=−0.48±0.41(stat)±0.07(syst) for the invariant mass of the KS0η system up to 2.1 GeV/c2.
A search for the decays B+→hcK+ and B0 → hcKS0 is performed. Evidence for the decay B+ → hcK+ is found; its significance is 4.8σ. No evidence is found for B0 → hcKS0. The branching fraction for ...B+→hcK+ is measured to be (3.7−0.9+1.0 −0.8+0.8)×10−5; the upper limit for the B0 → hcKS0 branching fraction is 1.4×10−5 at 90% C.L. In addition, a study of the pp¯π+π− invariant mass distribution in the channel B+→(pp¯π+π−)K+ results in the first observation of the decay ηc(2S) → pp¯π+π− with 12.1σ significance. The analysis is based on the 711 fb−1 data sample collected by the Belle detector at the asymmetric-energy e+e− collider KEKB at the ϒ(4S) resonance.
Observation of the Decay Bs0 → K0 K ¯ 0 Schwartz, A. J.; Aihara, H.; Ayad, R. ...
Physical review letters,
04/2016, Letnik:
116, Številka:
16
Journal Article
Recenzirano
Odprti dostop
We measure the decay B$^{0}_{s}$ → K0K¯0 using data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+e– collider. The data sample used corresponds to an integrated luminosity of ...121.4 fb–1. We measure a branching fraction B(B$^{0}_{s}$ → K0K¯0) = 19.6$^{+5.8}_{–5.1}$(stat.) ± 1.0(sys.)±2.0(NB$^{0}_{s}$B¯$^{0}_{s}$)×10–6 with a significance of 5.1 standard deviations. Here, this measurement constitutes the first observation of this decay.
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